Various means are known in the art for providing feedback to drivers of motor vehicles about the state of the vehicle or its surroundings. For example, feedback may be used to warn drivers about a state or event.
Visual and audible indicator means are most common for providing feedback to drivers. However, particularly in the context of warnings, haptic feedback has also been found to be effective and desirable. For example, it is known to provide lane departure warnings to drivers via haptic feedback.
Haptic feedback may, for example, be delivered via a vehicle's steering wheel. In particular, the steering wheel may be caused to vibrate to provide a warning to be sensed by the driver's hands. It is known to provide vibrations with dedicated vibration means, such as an electric motor and imbalance, within the steering wheel or within the steering column. However such dedicated means increase complexity, weight and cost, particularly when mounted within the steering wheel where electric routing poses additional difficulty.
DE 10 2011 056 042 A1 exemplifies a haptic feedback system which makes use of a steering column adjustment motor for providing haptic feedback to the steering wheel. DE 10 2011 056 042 A1 also suggests that a steering assistance servo could be used to impart vibration to the steering column. However, the haptic feedback exemplified in this document tends to feel artificial and distinct from the feedback received via the wheels of the vehicle when driving over a rumble strip. Rumble strips are safety formations on roads designed to alert inattentive drivers to potential danger by causing a tactile vibration and audible rumbling, transmitted through the wheels into the car body. A rumble strip is usually either applied to a road in the direction of travel along an edge- or centerline, to alert drivers when they drift from their lane, or in a series across the direction of travel, to warn drivers of a stop ahead or nearby danger spot.